1. Field of the Invention
This invention relates to an electric power supply control device, an image forming apparatus, a control method of an electric power supply control device, and a control program for an electric power supply control device. In particular, this invention relates to an electric power supply control device, an image forming apparatus, a control method of an electric power supply control device, and a control program for an electric power supply control device which include a DC/DC converter for performing intermittent oscillation.
2. Description of the Related Art
An electric power supply control device is used for electronic devices, such as an image forming apparatus (an MFP (Multi Function Peripheral) having a scanner function, a facsimile function, a copying function, a function of a printer, a data transmitting function and a server function, a facsimile device, a copying machine, a printer, or the like). An electric power supply control device may have a DC/DC converter which performs intermittent oscillation.
Traditionally, there are methods as below for improving efficiency of a DC/DC converter in an electric power supply control device. More specifically, outputting electrical voltage of a low voltage electric power supply is reduced, monitoring electrical voltage at a connection part between the low voltage electric power supply and the DC/DC converter.
Document 1 below discloses a DC/DC converter which can improve the efficiency by an electric power controlling method in which outputting electrical voltage of a low voltage electric power supply is reduced, monitoring electrical voltage at a part where the DC/DC converter is connected with the low voltage electric power supply.
Document 2 below discloses an electronic device which measures an electrical current at a part where the DC/DC converter is connected with the low voltage electric power supply. The electrical voltage between a maximum and a minimum of an allowable input electrical voltage range of the DC/DC converter load is output, so that the measured electrical current is at the lowest level.
Document 1: Japanese Translation of PCT International Application Publication No. 2012-505631
Document 2: Japan Patent Publication No. 2013-99013
During sleeping of the electronic device, a predetermined amount of electrical voltage (for example, 5V) is output from the low voltage electric power supply to the electric power supply control device, similarly as the normal condition. At this time, lower electrical voltage (electrical voltage which is equal to or less than 5V) is made by the DC/DC converter and used in the electric power supply control device. There is a limit on improving further efficiency with outputting 5V for the electric power supply circuit. The effect of reducing switching loss has a much greater impact on improving efficiency of the DC/DC converter. Hence, it is desired for improving the efficiency of the DC/DC converter that intermittent oscillation is maintained and the number of times of switchings is reduced when the load is light.
According to the electric power managing method disclosed in above Document 1, there is a limit on improving efficiency. More specifically, the input electrical voltage is decreased as long as the output is maintained. Hence, a DC/DC converter having an intermittent oscillation behavior function may not be able to perform intermittent oscillation.
According to the electronic device disclosed in Document 2, a structure of the equipment is complicated. More specifically, the device should measure the input electrical currents by varying the input electrical voltage of the DC/DC converter, determine the electrical voltage where the measured electrical current is a minimum, and store the same.
This invention is to solve the problems. The object is providing an electric power supply control device, an image forming apparatus, a control method of an electric power supply control device, and a control program for an electric power supply control device which can increase power converting efficiency.